The present invention relates to a drive shaft serving for the pivoting of the reed teeth about a pivot for a wave-type loom in which the reed teeth are formed of elongated thin blades, the wide sides of which are perpendicular to the shaft and which have one edge resting against the shaft.
Wave-type or undulating looms with blade-shaped reed teeth are known in which the latter are so moved by means of screw shafts, i.e. drive shafts which have a helical profile, that they as a whole carry out an undulatingly progressive movement and thereby beat the filling threads against the fell of the cloth. It is also known to use the undulatingly progressive movement of the reed teeth simultaneously for advancing the filling thread insertion members or shuttles.
In these undulating looms, the blade-shaped reed teeth have their wide sides perpendicular to the screw shafts which swing or pivot them about a pivot shaft around which they swing to lie with their narrow sides on the drive shafts. Accordingly, there is the danger that during the course of operation the blades will gradually work their way into the drive shafts producing thin grooves in the latter. As a result, the amount of swing or pivoting motion of the blades becomes inaccurate which in turn causes an irregular beat-up of the cloth.
It has been attempted to produce screw shafts of steel and provide them with a hardened chrome layer in order to prevent the formation of grooves. This measure however has failed to produce the desired results. In particular it has been found that in the case of metal reed teeth, contact rust is formed or wear of the reed teeth takes place.
For this reason screw shafts whose outer layer consists of plastic have been employed. If the plastic is arranged over an inner core of metal in such a shaft, the shaft is imparted the necessary strength. However, the blades still cut-in to such an extent that the life of the screw shaft must be considered insufficient for use on a loom. Since the reed teeth extend between the warp threads, when one of the customary types of lubrication is used, the cloth to be formed is dirtied. Furthermore, a resinification of the reed teeth takes place whereby the movement of the reed teeth is strongly impeded with the result that an increased load is exerted on the screw shaft by the reed teeth during operation.
The closest prior art known to applicants in connection with this application is U.S. Pat. No. 3,687,171.